Name: ________________________________________________ Date: ________________
Chemistry 112: Paper Chromatography of Food Dyes
Purpose: To use paper chromatography to separate and identify food dyes in various samples.
Materials:
Paper
Food colouring –
(Standard Colours)
Pencil
Four other items of
your choice.
Ruler
0.1% NaCl solution
Scissors
Glass Beaker
Toothpicks
Chromatography
paper
Procedure:
1.
Label a 5 cm x 10 cm strip of chromatography paper USING a PENCIL! (DO NOT DRAW
THE LINES)
Table 1: Food Colouring Samples
Names:________________________
RED
YELLOW
GREEN
BLUE
O
O
0
0
2. Use a different toothpick to place a single dot of food coloring approximately 1 – 1.5 cm
from the bottom of your chromatography paper (MUST NOT COME IN CONTACT WITH THE
NaCl AT THE BOTTOM OF YOUR BEAKER). Allow the spots to dry.
3. Add the 0.1% NaCl solution to the beaker so that it just covers the bottom.
4. Wrap the top edge of the chromatography paper around the pencil. Hang the paper so that
it touches the solution at the bottom of the beaker. Be careful: Have the lower end of
the paper touch the solution but have the spots of colour above its surface. Wait.
5. When the solution reaches the top of the chromatography paper, remove the paper and
allow it to dry.
6. Prepare a second strip in the same manner replacing the food colouring with 4 other samples
of your choice. (Remember to call it Table 2, and to write down what you are testing at the
top of each column!)
* For the Jellybeans or Smarties: Wet the candy, blot with paper towel to remove excess
water, and press the candy onto the chromatography paper.
*For the Kool-Aid and/or the Fun and Funky Food Colouring follow the procedure as above.
7. Complete the analysis.
Analysis: Please staple your tables in the space provided and using your data, answer the
following questions using complete sentences.
Name: ________________________________________________ Date: ________________
Chemistry 112: Paper Chromatography of Food Dyes
Table 1:
1.
Table 2:
If a food colour sample yields a single streak, it is usually a pure compound.
a.
Which of samples from Table 1 consist of pure compounds? From Table 2?
Table 1:
____________________________________________________________________
____________________________________________________________________
Table 2:
____________________________________________________________________
____________________________________________________________________
b. Which of the samples from Table 1 are mixtures of compounds? From Table 2?
Table 1:
____________________________________________________________________
____________________________________________________________________
Table 2:
____________________________________________________________________
____________________________________________________________________
2. Food colours often consist of a mixture of three dyes: Red # 40, Yellow # 5 and
Blue #1. Identify each spot or streak on your tables as Red # 40, Yellow # 5 or Blue
#1.
3. Paper Chromatography separates polar covalent compounds on the basis of their relative
polarities. The most polar dyes migrate the fastest and appear at the top of the paper.
a. Which dye, from Table 1, is the most polar? Which dye, from Table 1, is the least
polar? Least polar _______________________ Most polar___________________
b. Which dye, from Table 2, is the most polar? Which dye, from Table 2, is the least
polar? Least polar _______________________ Most polar___________________
What is Yellow-5? (Tartrazine is the proper name). It s a yellow azo dye (synthetic color
that contain an azo group, -N=N-, as part of the structure)that is derived from coal
tar. It is used as a food coloring and has been banned in Finland, Norway, Austria, and
Germany for quite sometime.
Name: ________________________________________________ Date: ________________
Chemistry 112: Paper Chromatography of Food Dyes
What does it do?
Well to foods and other products of course it colors it yellow, but what does it do to the
estimated 360,000 Americans that have allergies reactions to it? Reactions range from a
little bit of indigestion to clinical depression, anxiety, vision problems, feeling like your
suffocating, migraines, it can also cause you to miss out on a lot of sleep. Some of these
symptoms can be caused from just from very small amounts of exposure to Tartrazine and
can last as long as 72 hours!! It is actually believed that there is a link between children who
suffer from hyperactivity disorders and Tartrazine, which means that some seem to think
that Tartrazine itself is what causes the hyperactivity, not problems with the children.
Some drugs that are made to help children with hyperactivity disorders are made with
Tartrazine, which means it could actually be worsening the problem. .
It is authorized for
use in Canada and the United States.
Where is it found? Bread, butter, ice cream, milk, jams, jellies (with pectin), pickles,
tomato ketchup, margarine, cheese, smoked fish, icing sugar, sherbert
What is Red Dye #40 (Allura Red) Has been banned in Sweden, Norway, Japan, Italy,
Israel, France, Austria, UK, Austraia.
What does it do?
Originally developed to replace red dye # 4 which was banned in 1976. The FDA approved it
even thought the testing was deficient. The experiments did not include two species of
animals as stipulated by the guidelines of testing food additives. The British and Canadian
Governments would not approve RD # 40 unless additional test were done. In 1976 Allied
Chemical completed the tests and the results indicated that the dye caused cancer in mice.
A US pathologist was quoted as saying that it had all the properties of a carcinogen.
It is
authorized for use in Canada and the United States.
Where is it found? Bread, butter, ice cream, milk, jams, jellies (with pectin), pickles,
relishes, sherbert, prepared fish and meat, salted shrimp, smoked fish.
What is Blue Dye #1 (Brilliant Blue) is a coal tar derivative. Banned in all European
Commonwealth countries, as well as Austria, Finland, Norway, Sweden and Switzerland.
Where is it found? Bread, butter, ice cream, milk, jams, jellies (with pectin), pickles,
relishes, sherbets, prepared fish and meat, salted shrimp, smoked fish and ketchup.
What does it do? Studies have shown that it causes cancer when ingested, as well as
malignant tumors in rats at the site of injection. Other studied have shown that it
promoted breast tumors in test animals and increased the incidence of kidney tumors in
male mice. The FAO/WHO recommended that it NOT be used. It is authorized for use in
Canada and the United States.
Question: Should all food be labeled if it contains any of these compounds? Would you still
consume them, knowing this? Explain.
Name: ________________________________________________ Date: ________________
Chemistry 112: Paper Chromatography of Food Dyes